Such automatic fall detection systems are known. They are used to detect fall incidents of a user and report such incidents to a remote care provider who may then take appropriate action. To that end, the detection systems generally comprise a sensor module, to be worn by the user, for collecting movement data of his body, for instance acceleration data. The detection systems further comprise evaluation logic, to detect an impact in the collected movement data. Such impact will occur when the user hits the ground during a fall. However, such impacts may also occur through other events, such as a sudden movement of the user or a collision with his environment. Consequently, the detection of an impact in the acceleration data is not sufficient to positively identify the occurrence of a fall. Therefore, most detection systems are arranged to detect the existence of other pointers, indicative for a fall. It may for instance be verified whether the impact is accompanied by a change in orientation of the user, e.g. a change in posture from standing to lying down. Only in such case the system may raise an alarm to a remote caregiver. Thus, the number of false alarms can be reduced, thereby increasing the reliability of the system and its acceptance by its users.
However, these known fall detection systems may suffer from several drawbacks, as a result whereof false alarms may still occur.
For instance, it frequently occurs that the sensor module itself is dropped from the user's body, for instance during changing clothes. It also occurs that the sensor module has been temporarily placed on a table or the like, and is accidentally knocked there from. In such cases, the known systems will generate an alarm, where they obviously should not.
Other problems may occur when the sensor module is attached to the body in an improper, i.e. disoriented way. This may affect the system's ability to discern changes in the orientation of the user, and may cause the system to draw the wrong conclusions regarding the existence of a fall. More particularly, the system may produce an alarm where there is no fall (a so called false positive), or worse, produce no alarm where there is a fall (a so called false negative). Either situation should be avoided, because it may seriously undermine the confidence in the system.